This invention is directed toward an improved tree cutting mechanism for a tree harvester.
The invention is also directed toward a felling head for a tree harvester incorporating the improved tree cutting mechanism.
Tree harvesters at the present time employ chain saws or shears to cut down trees being harvested. Both cutting methods have disadvantages however. Chain saws tend to bind in the cut causing breakage and thus frequent repair. In addition, frequent maintainence is required. Shears are simple in operation, do not bind and require much less maintainence than chain saws. However the cutting action of the shears often causes the tree to split or shatter from its butt end resulting in waste.
One approach being developed to overcome the problems of using chain saws or shears is to use a large circular saw on the felling head, mounted for rotation on a vertical axis. The large circular saw requires little maintainence, provides a clean cut, and binding is not a serious problem. However, the circular saw must be quite large in diameter in order to be able to cut through large trees. Due to the central mounting of the saw less than one half of its diameter is available to cut through a tree. Thus, if two foot diameter trees are to be cut, a saw close to five feet in diameter must be employed. Such a large saw requires a great deal of power, making it expensive to operate. In addition, maintainence and repair in the field is difficult because of its size. The initial cost of the saw is also high.